161698261 has 2 divisors, whose sum is σ = 161698262. Its totient is φ = 161698260.

The previous prime is 161698259. The next prime is 161698289. The reversal of 161698261 is 162896161.

161698261 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 156725361 + 4972900 = 12519^2 + 2230^2 .

It is a cyclic number.

It is not a de Polignac number, because 161698261 - 2¹ = 161698259 is a prime.

It is a super-2 number, since 2×161698261² = 52292655220848242, which contains 22 as substring.

Together with 161698259, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (161698231) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80849130 + 80849131.

It is an arithmetic number, because the mean of its divisors is an integer number (80849131).

Almost surely, 2^161698261 is an apocalyptic number.

It is an amenable number.

161698261 is a deficient number, since it is larger than the sum of its proper divisors (1).

161698261 is an equidigital number, since it uses as much as digits as its factorization.

161698261 is an evil number, because the sum of its binary digits is even.

The product of its digits is 31104, while the sum is 40.

The square root of 161698261 is about 12716.0631093118. The cubic root of 161698261 is about 544.7975130845.

The spelling of 161698261 in words is "one hundred sixty-one million, six hundred ninety-eight thousand, two hundred sixty-one".